1. Field of the Invention
The present invention relates generally to a mobile communication system, and in particular, to a paging apparatus and method for a multimedia broadcast/multicast service (MBMS) service.
2. Description of the Related Art
These days, due to the development of the communication industry, a service provided by a code division multiple access (CDMA) mobile communication system is developing into multicasting multimedia communication for transmitting not only voice service data but also high-capacity data such as packet data and circuit data. In order to support the multicasting multimedia communication, a broadcast/multicast service is required in which one data source provides a service to a plurality of user equipments (UE). The broadcast/multicast service can be divided into a cell broadcast service (CBS), which is a message-based service, and a multimedia broadcast/multicast service (MBMS) supporting multimedia data, such as real-time image and voice, still image, and text.
Network architecture for providing an MBMS service in a mobile communication system will now be described with reference to FIG. 1.
FIG. 1 schematically illustrates network architecture for providing an MBMS service in a mobile communication system. Referring to FIG. 1, a multicast/broadcast service center (BM-SC) 110 is a source that provides an MBMS service stream, and the BM-SC 110 delivers an MBMS service stream to a transit network (NW) 111 after scheduling. The transit network 111 is a network existing between the BM-SC 110 and a serving General Packet Radio Service (GPRS) support node (SGSN) 100, and delivers the MBMS service stream provided from the BM-SC 110 to the SGSN 100. It is assumed herein that the SGSN 100 can be comprised of a gateway GPRS support node (GGSN) and an external network, and there exist a plurality of UEs desiring to receive the MBMS service at a certain time, i.e., UE1 104, UE2 105 and UE3 106 belonging to a Node B Cell 1 102 and UE4 107 and UE5 108 belonging to a Node B Cell 2 103. The SGSN 100, receiving the MBMS service stream from the transit network 111, performs MBMS service-related control on subscribers (or UEs) desiring to receive an MBMS service. For example, the MBMS service-related control includes management of MBMS service accounting-related data for each subscriber and selective transmission of MBMS service data to a particular radio network controller (RNC) 101. In addition, the SGSN 100 forms and manages an SGSN service context for an MBMS service X, and delivers a stream for the MBMS service to the RNC 101. The RNC 101 controls a plurality of Node Bs, and transmits MBMS service data to a Node B where there exists a UE requesting the MBMS service among Node Bs managed the RNC 101 itself. In addition, the RNC 101 controls a radio channel established to provide the MBMS service, and forms and manages an RNC service context for the MBMS service X by using the MBMS service stream provided from the SGSN 100. As illustrated in FIG. 1, only one radio channel is formed between one Node B, e.g., the Node B Cell 1 102, and the UEs 104, 105 and 106 belonging to the Node B Cell 1 102. Furthermore, a home location register (HLR), though not illustrated in FIG. 1, is connected to the SGSN 100 and performs subscriber authentication for the MBMS service.
In addition, as mentioned above, the RNC 101 and the SGSN 100 manage service-related information according to MBMS services, and the service-related information managed according to MBMS services is defined herein as “MBMS service context.” For example, information stored in the MBMS service context includes a list of UEs desiring to receive an MBMS service, i.e., UE identifiers (IDs) of UEs desiring to receive the MBMS service, a service area where the UEs are located, and a quality of service (QoS) needed to provide the MBMS service.
A procedure for providing an MBMS service will now be described herein below.
In order to provide the MBMS service, fundamental information on the MBMS service must first be transmitted to the UEs, and if the UEs receiving the fundamental information on the MBMS service desire to receive the MBMS service, then a list of the UEs requesting the MBMS service must be transmitted to a network. Upon receiving the list of the UEs desiring to receive the MBMS service, the network must page the UEs and set up a radio bearer for providing the MBMS service. After setting up a radio bearer between the network and the UEs, the network provides the MBMS service over the set radio bearer. Meanwhile, if the MBMS service is ended, the fact must be notified to all UEs. Then, all the UEs receiving the MBMS service must release all resources assigned for the MBMS service, for normal MBMS service.
However, in an existing communication system providing an MBMS service, there has been provided no detailed plan for the above-stated procedure for providing the MBMS service, especially a procedure for paging a UE. Accordingly, there is a demand for a method of paging a plurality of UEs receiving the MBMS service.